OKANAGAN FALLS, B.C. -- Calmer winds overnight have helped crews make good progress in the fight against a wildfire burning five kilometres southwest of Okanagan Falls, B.C.

The Wildfire Management Branch says the blaze is now 70 per cent contained.

Since it was reported Sunday afternoon, the fire has scorched an estimated 70 hectares, or just under three-quarters of a square kilometre of grassland, sage brush and open timber, about 20 kilometres south of Penticton.

Twelve properties in the area remain on evacuation alert issued just before 6 p.m. Sunday as gusty winds fanned the fire.

Fire information officer Melissa Welsh says the blaze is much less aggressive and a total of 42 firefighters supported by three helicopters are working to complete guards around the perimeter.

Welsh says a cause remains under investigation but humans likely sparked the flames.